1. Field of the Invention
The present invention relates to a run flat support body for a pneumatic tire. Particularly, the present invention relates to a run flat support body for a pneumatic tire, which achieves a good balance between run flat durability of the run flat support body to be inserted inside the pneumatic tire and workability for mounting the run flat support body on a rim (hereinafter sometimes referred to as “mounting”).
2. Background Art
As measures enabling a vehicle to make an emergency running to a repair shop such as a gas station when a pneumatic tire of the vehicle is punctured while the vehicle is running, numerous proposals have been made, in each of which a core is inserted as a run flat support body in a hollow part of the pneumatic tire mounted on a rim of a wheel.
Among the proposals, there is a run flat support body, which is formed of an annular shell having left and right bifurcated leg parts on a cross section in a width direction of the tire, and which is formed in a manner where elastic rings are attached respectively onto the both leg parts. The run flat support body has an advantage that a conventional wheel can be used as it is without making any substantial modifications to a rim structure of the wheel. However, for the run flat support body formed as described above, it is required to compose the elastic rings supporting of a material having high rigidity so as to secure durability of the run flat support body during run flat driving.
For this reason, in Patent Document 1, it is proposed that the durability of the run flat support body is improved by covering a periphery of the elastic rings with a fiber reinforcing layer. However, if the run flat support body has a structure in which simply the elastic rings are covered with the fiber reinforced layer, the rigidity of the elastic rings becomes too high. Because of that, a problem occurs in which workability for mounting at a time of mounting a run flat support body onto the rim of the wheel becomes extremely poor. That is, when mounting the run flat support body onto the rim of the wheel, the mounting is performed by bending the elastic rings in an axial direction of the tire by applying a large lateral force to the run flat support body. Accordingly, when the bending rigidity of the elastic rings becomes too high as described above, a problem arises in which a difficulty occurs in the mounting operation.
Patent Document 1: Japanese patent application Kokai publication No. 2004-98882.